Now that many episodes have been out for quite some time, I kinda wanted to revisit theories on Boruto’s eye. note that this contains major spoilers for both Boruto the anime and Naruto: the last movie.
I’ve been rewatching the currently released 14 episodes of the anime, and passing over episode 8 gave me some serious insights to what boruto’s eye might be. Episode 1 begins with a snapshot of Boruto’s eye, with a patterning similar to what we would consider a sage-mode. This is coupled with his byakugan-looking iris and pupil and black eye whites, which match the patterning. The visuals coupled with the fact that Hinata is his mom gives us some indication that his eye definitely has a very close relationship with the byakugan.
Quick aside to review the byakugan, it’s visual powers allow its users to see through solid objects and see and strike the flow of chakra within people’s bodies. This is very evident in all of Neji’s and Hinata’s attacks in shippuden, as well as Himawari’s amazing ability to one-shot naruto in the special Naruto: the day he became the hokage.
Next, we note the original Tenseigan from Toneri in the Naruto: The Last movie. It has a pale-blue/teal iris with a flowering pattern and white eye whites. Other notable features of the Tenseigan is the direct relationship it has with the byakugan, noting how the tenseigan requires the byakugan with the pure chakra of the otsutsuki. when Toneri lost his Tenseigan, it simply reverted or was removed from his (hanabi’s) byakugan. Also note how Toneri specifies that the tenseigan requires the purest byakugan, something which Hinata (and presumably Hanabi) had, which is Toneri’s reason for obsessing over Hinata. Hinata, being boruto’s mom, might have passed down the “purest” byakugan into Boruto (and himawari). Additionally and importantly to note, the “tenseigan sage mode” appears to have black patterning when Toneri activates it, though the coloration cannot be known definitely since the aura covers and possibly discolors his entire body.
Side note: in the movie, it’s noted that the Hyuga are descendants of Hamura Otsutsuki, who first awakened (created? birthed?) the byakugan, and most likely wrote the process for awakening the tenseigan.